1. Field of the Invention
The present invention relates to a composite fiber and a method for manufacturing the same, and a substrate containing the composite fiber and a method for manufacturing the same. In particular, the present invention relates to a composite fiber having a high surface area and high flexibility and a method for manufacturing the same, and a substrate containing the composite fiber and a method for manufacturing the same.
2. Description of the Related Art
FIG. 1 is a schematic cross-sectional view of conventional composite fibers as disclosed in US Patent Publication No. US2008/0108265, titled “Method for Manufacturing High Surface Area Fiber and Textile” and US Patent Publication No. US2008/0105612, titled “Composite Filter Media with High Surface Area Fibers”. According to these patents, by adopting a sea-island composite fiber technology, a composite fiber 1 is formed when an island component 10 is wrapped by a sea component 11. A cross section of the composite fiber 1 is in an oval shape or oblong shape. The island component 10 is in a centipede-like shape, and includes a central portion 12 and a plurality of extension portions 13. The sea component 11 wraps completely around the central portion 12 and the extension portions 13. There is a maximum length L1 of the central portion 12 and a maximum length L2 of the sea component 11, wherein L1 is approximately 80% of L2.
A plurality of composite fibers 1 may be used to manufacture a textile, the textile is subjected to a dissolving and removing processing, and the sea component 11 is dissolved and removed to obtain a fiber shaped in the centipede-like arrangement (only the island component 10 is left). The fiber has many whiskers (the extension portions 13), providing a high surface area.
Since the cross section of the conventional composite fiber 1 is in an oval shape or oblong shape, the ratio of the major axis to the minor axis is excessively large, so the composite fiber 1 will be deformed when an external force is applied. Therefore, the composite fiber 1 cannot be easily processed by methods such as false twist and weaving in post processing. In addition, since the sea component 11 is required to completely wrap the island component 10, the ratio of the dimensions of the sea component 11 cannot be too low, meaning that the ratio of the dimensions of the sea component 11, which has to be dissolved and removed, is high. Furthermore, in a textile manufactured by the composite fiber 1, the stiffness of a small unit of the island component 10 is high and its flexibility is poor due of its H-like shape.
Therefore, to solve the aforementioned problems, it is necessary to provide an innovative and inventive composite fiber having both a high surface area and flexibility and a method for manufacturing the same, and a substrate containing the composite fiber and a method for manufacturing the same.